We are selectively breeding mice that drink sufficient EtOH to achieve high (>100 mg%) blood ethanol concentrations (BECs) during a 4 hr exposure to 20% EtOH. The HDID-1 line will be in its 20th selected generation (S20) at the time of the renewal. A second replicate (HDID-2) was started in Year 6 and will be in generation S13. The principal goal of this renewal is to continue to select these two lines. As animals are selected, we will breed additional naive mice each generation and ship them to other INIA-West investigators for their specific aims, as well as to other interested investigators. To assess pleiotropic gene effects, we will characterize the HDID lines and their HS/Npt control line for several responses to ethanol. Co-I Tamara Phillips is examining the circuitry underlying DID, using intracranial injection of test compounds to inactivate specific brain areas temporarily. Use of transmitter-specific drugs will also be considered in regions where inactivation is effective for manipulation of afferent or efferent pathways based on INIA-West targeted circuits. As relevant brain areas are identified, we will explore how intracranial injections modulate drinking microstructure. With a supplement, we obtained equipment to assess feeding and drinking microstructure simultaneously and will analyze this in the lines. We will test the hypothesis that drinking following chronic intermittent exposure to ethanol vapor is enhanced in HDID mice. The microstructure of drinking will also be explored during this post-CIE drinking.